# Tagged Questions

Force per unit area.

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### Coherence of pressure and mass flow in a pipe [closed]

What is the coherence of pressure and mass-flow in a horizontal pipe? Let's assume I have just one pipe with pressure = 1.5 bar at the input and through pressure-losses 1.2bar at the output. Is there ...
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### Is the force exerted by the container on the fluid and the force exerted by the liquid on the container equal?

I came across a question where i was asked to find the force exerted by the walls of a frustum shaped bucket on a liquid inside it . I found the force exerted by the liquid on the walls of the bucket ...
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### Extract energy from the atmosphere? [closed]

Let's say we would fill a long tube with water. Let's say the tube is 1km in height. At the bottom of this tube, the pressure should be much higher than the top. Also, the tube would lead into a ...
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### What causes the balloon to pop when we push with needle onto it's surface?

I am a bit puzzled because I can see two possible reasons, first one is more common and the other one makes sense too, so here they go: 1) balloon pops because of the fact that after pressure is ...
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### The Balloon Model for Human Ventilation

The balloon model is often used to show how ventilation works in the human lungs. You pull on the diaphragm, expanding the volume of the container, and the balloon begins to fill up. My understanding (...
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### Calculation of water pressure [closed]

I have a water tank of 750Ltr capacity installed at a height of 7.5M from ground. How to determine the range of pressure gauge required to measure the pressure from ground level.
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### Water + RF + Spark = Continuous Fire

Can anyone explain the physics of what is happening in the following video? https://youtu.be/p8xYUDiSGDk?t=37 Is this process Radiolysis? At what radio frequency & power level is h20 ...
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### Why does individual N2 molecule rise when heated?

I get that hot air is less dense so it rises due to floatation and all, but what happens to one individual diatomic Nitrogen that it increases it's distance from ground? And why is it that the air is ...
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### How to move a bubble which is trapped by the capillary pressure?

I have a question about how to move a trapped bubble in a tube. If we assume to have a horizontal tube, with water on each side of the bubble. The point to the left of the bubble is point 1, while ...
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### How to Calculate Pressure From Earth up to Space at Certain Height? [duplicate]

https://en.wikipedia.org/wiki/Vacuum#Measurements_relative_to_1_atm https://en.wikipedia.org/wiki/Pressure_measurement#Thermal_conductivity I wonder if there's a clear equation for this calculation. ...
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### Difference of water pressure

We know that $P = \rho gh$, so is it true that water pressure at 2nd floor will be higher than water pressure at 9th floor of a 12 story building?
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### Liquid phase is a highly compressed gaseous phase

$\mathbf{Q:}$ While teaching "Real Gases", my professor remarked last day that "Liquid phase is a highly compressed gaseous phase." But he did not explain the reason behind it and left it as food for ...
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### Injected gas versus pressure rise

Very simple concept for some, but quite honestly I’m striving to grasp: Premises: You have a $20 \text{ m}^3$ pressure vessel. You start filling it with gas. You see a rise in the gauge pressure ...
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### Pressure at ground level and at sea level

1atm = 101325pa 1bar = 100000 pa 1atm = 1.013 bar 1bar = 0.987atm From wiki: The bar is a metric (but not SI) unit of pressure exactly equal to 100000 Pa.[1] It is about equal to the atmospheric ...
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### How does speed of gas molecules change with pressure? [closed]

A thought experiment. I have a box of fixed dimensions, inside this box I have molecules of $H_2$ at constant temperature. I'll be gradually increasing pressure inside the box and the temperature ...
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### What is the energy source if a tall water tank is used to transfer floating objects upwards instead of cables with motors?

Suppose I want to transport some logs from the ground to the roof of a tower. Originally I can use a lift, or some cables, or even move the logs upwards manually; then the energy is converted to the ...
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### why is pressure more convenient than force while dealing with fluids? [duplicate]

If two equal and opposite forces act on a surface, can I say the pressure is zero because the net force is zero? How can pressure be non directional when force as a direction? How can the pressure of ...
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### Velocity of water from a certain depth

I was curious to know does water come out of a certain depth when there is a difference in pressure, and also if it does come out of a certain depth, at what velocity does it travel at? So, ...
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### Pressure Change in Supersonic Wind Tunnel [closed]

As far as I know, the total pressure changes across a shock wave. How is this possible if you are in the atmosphere and atmospheric pressure isn't changing? Is energy lost due to entropy in ...
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### Rate of applied force versus material failure?

Question: Does the rate at which a force is applied to an object determine the maximum force reached that mechanically fails the object? If so, what are the concepts that need to be understood to ...
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### Effect of radiation pressure on Earths orbit in large timescales

I have seen some posts concerning the radiation pressure exerted by the Sun on Earths surface (Force on Earth due to Sun's radiation pressure). Though it is fairly small may it have a considerable ...
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### Perfect fluid and EM tensor in rest frame

I see that we use perfect fluid which is characterized by a energy density and isotropic pressure for general forms of matter. When guessing the values of energy momentum tensor indices we can use ...
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### How does a pop pop boat work?

I have been reading about the pop pop boat on wikipedea. What I don't understand is after the hot water is ejected the vacuume gets created, so when the same amount of water will be sucked in the boat ...
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### Velocity of a leak in a closed water tank

Bernoulli's equation states $P_1+{1\over2}\rho v_1^2+\rho g h_1 = P_2+{1\over2}\rho v_2^2+\rho g h_2$ In a classic "water tank with an open top and a leak" scenario, "point 1" is the surface water ...